the word can be broken into ob+STREET+PERU..streets in peru are very noisy because of traffic.

51 3

by viveksa7

obstetrician is the one who deliver babies...obstreperous sounds like obste+pair ous so pairing all those obstreticians and delivering the babies all at a time then all the babies after deliever they make a lot of noise....

31 69

by rizvi

OBSTRE- word is used for small babies in obstretrician.
Small babies are very noisy and bossy(they want things done their way).